Voice dialog systems are used in telecommunications networks, especially in the fixed network and cell phone network domain to route a caller in a dedicated manner through a complex service offering. The caller can use for example a fixed network telephone or mobile phone as a communications terminal. A call of the caller is accepted by a voice dialog system and processed such that questions are posed to the caller fully automatically using natural speech in order to determine what the caller wants. The caller can carry on partially or fully automated dialogs with the voice dialog system that is also called a “voice portal.”
An especially simple form of the voice dialog system in the form of individual word recognition that is also called interactive voice response (IVR) is common. Using the IVR simple voice navigation in telephone systems is possible. For example the caller is questioned as follows by the voice dialog system:                “If your request relates to a bill, please say bill.”        “If your request relates to a complaint, please say complaint.”        “If you would like to talk to a representative, please say representative.”        
After the voice dialog system has posed all questions, it awaits a voice input of the caller. The caller thereupon expresses himself verbally, his disclosing to the voice dialog system via the telephone a speech element in the form of a word. At this point a speech recognition process takes place automatically.
This speech recognition process is based on signal comparison of the specific acoustic caller statement with words filed as speech elements. If agreement of the transmitted speech element with a filed word can be ascertained, the statement is considered recognized and can trigger a fixed action in the voice dialog system. For example the voice dialog system can pass into a submenu and from it other headings of the submenu can pose pertinent questions. Alternatively the voice dialog system can also directly initiate a certain service after statement recognition, the caller leaving the voice dialog system.
When the caller statement is not recognized, in the current voice dialog system a user-unfriendly “reject” is executed that is reflected in a statement of the voice dialog system of the following form: “Unfortunately I was not able to understand you, please repeat.” The voice dialog system requires a repeated voice input. For the caller the repeated statement is burdensome and leads to his having to remain longer in the dialog system. The caller thus becomes impatient and dissatisfied; this can lead to the operator of the speech portal losing the caller as a customer or potential customer.